What is Hoplink?



Hoplink is a Calypso application dedicated to interoperability.

It is based on a very simple principle:

  • The portable object (card, SIM card, USB key, etc.) is interoperable; it means that the customer may use it in all transport networks which are Hoplink members.
  • The transport titles and contracts remain specific, and are not shared between the different operators; it means that Hoplink requires no clearing system between them.

Consequently, Hoplink is very simple to implement.

Hoplink answers mainly to two needs:

  • Interoperability between two different tariff areas (2 regions for example) for regular users.
  • Interoperability for occasional users who spend a few days in a city or a region.

Hoplink is a Calypso application within the portable object, beside the local application which is used daily for public transport ticketing by the customer. The specificity of Hoplink application is that the secure keys are shared between all operators which are Hoplink members (personalization, reloading and validation keys). Consequently, all the Hoplink operators may use the Hoplink application to register and validate their own tickets in the portable object of the customer.

Of course, it requires the operators to strictly respect some mandatory rules, in term of security requirements and also limited functional requirements, particularly not to delete a valid transport title from another operator.

Each operator Hoplink member decides which transport titles are offered to the customer through the Hoplink application. For example, he may decide to limit them to titles for occasional users, such as single tickets, one-day tickets, etc. and to interregional tickets, etc.


A Hoplink customer case

In order to better understand how it works, let’s take a concrete example of a customer using the possibilities of Hoplink.

“I live in the Brussels area, and I am a daily user of public transport in this city, taking the train from SNCB and the metro from STIB. So I have a MOBIB card, the unified card for all transport networks in Belgium. Of course, my monthly season ticket within my MOBIB card is accepted by both SNCB and STIB (it is tariff interoperable).

All MOBIB cards include a Hoplink application; so I know that I can use my personal MOBIB card in all other transport networks which are Hoplink members.

I have to go to Lille, in France, for 3 days, and I know that Lille is a Hoplink member: I go to Lille, free of mind, with my MOBIB card; in the Lille station, I go directly to a ticket machine, take my Mobib card and reload it with a 3 days ticket of Lille transport. This ticket is registered within the Hoplink application; of course it is accepted on all Lille validators.

It avoids me having to buy a specific media for my ticket and makes really my trip easier.”

With the new possibilities offered by the distant reloading systems on Internet or on mobile phones, the Hoplink service may be much better, offering a really seamless solution for the customer. Let’s again take the same example:

“Rather than buy my Lille ticket at a vending machine in the Lille station, I prefer to prepare my trip in Brussels: I connect on the Internet to the reloading web site of Lille, and, with my MOBIB card connected to my computer, I buy and load in the Hoplink area the 3 days Lille ticket. It avoids me having to waste time when arriving at the Lille station, to look for the vending machine, or to make a queue.”


Hoplink technical

Find all technical description of Hoplink, and particularly all the security mechanisms, in the Hoplink Specifications document.

Below is the typical representation of the file organization of a card with local and Hoplink applications.




How to join Hoplink?

If you are an operator or a transport authority which intends on using Hoplink, there are some requirements to follow:

  • Of course, to have implemented Calypso for your ticketing system (!)
  • To fill in the form of CNA member registration and to send it, indicating that your interest is to join Hoplink. If you are already a CNA member, you use the same form and mention it by checking the appropriate box. You may see all information about CNA membership in the CNA Membership tab.
  • To fulfill the requirements which are described in the Hoplink contract, about security and rules of usage. By signing this contact between you and CNA, you will engage in respecting all these requirements towards the whole community of Hoplink members. Please note that this contract has already been signed by numerous authorities and operators, and that no more modifications to its content are possible.
  • The acceptance as a Hoplink member is submitted to and validated by the assembly of the Hoplink members.


If you need complementary information, please call the following number:

+33 (0)1 77 11 81 16 or send a mail to hoplink@calypsonet-asso.org

Please send the signed contract to the following address:

Calypso Networks Association
Rue Royale, 76/2
B 1000 Brussels



Your Hoplink membership will be definitively validated after receipt of your payment for CNA membership (by bank account transfer).






How to implement Hoplink?


The complete operational procedure to implement Hoplink in your system, the management of keys, the certification process are described in the Hoplink Best Practices document.


To ensure a better level of interoperability, CNA proposes a set of mandatory tests to be realized at the level of the implementation of Hoplink in a ticketing system, in order to ensure that the applicative software respects the rules fixed for a normal behavior of the sale terminal and a compliant management of the contract area within the card.

Find here the guidelines for Hoplink conformity

For more information, you can send an email to certification@calypsonet-asso.org